Nutrition and Management: High Moisture Grain Production

This is a fact sheet from the Nutrition and Management section of the Alberta Feedlot Management Guide,Second Edition published September 2000. The 1200 page guide is available for purchase on CD-ROM.

Take Home Message

• High moisture barley (HMB) production is similar to dry barley except for harvesting and storage.
• HMB can be ensiled over a wide range of moisture levels from 22% to 40%.
• There are a number of agronomic advantages to harvesting barley as HMB.
• Advantages to feeding HMB are not as numerous.
• HMB is most attractive where wet harvest conditions reduce the quality and value of barley harvested dry.

Production of high moisture barley (HMB) is similar to growing barley for dry grain harvesting. The difference is, however, in the harvesting. Production from the different varieties of barley vary, depending on the location where they are grown. Management and variety selection should emphasize grain rather than forage production. Although all varieties of barley thresh better at moisture levels above 25%, there are some varietal differences. Producers are encouraged to seek local information about varieties and crop management practices best suited for their particular area. Because kernel moisture level is critical for proper ensiling, staggered seeding dates may help to insure a constant supply of barley at a desirable moisture content.

Harvesting

HMB can be ensiled over a wide range of moisture levels from 22% to 40%. Barley reaches maturity and maximum yield at about 40% kernel moisture. This is about 10 to 21 days before barley could be stored safely as dry grain. The optimal moisture level is between 25% and 35%, depending upon the storage method. This occurs about 10 to 15 days earlier than conventional harvesting. This gives HMB an advantage in areas where risk of adverse weather conditions at harvest time, decrease the opportunity to harvest dry grain.

Accurate moisture content is best determined using actual drying methods. Surface moisture from dew and rain can result in errors when moisture is estimated using moisture meters which measure electrical conductivity. With experience producers can learn to estimate moisture content adequately without testing. Rolled barley, in the proper moisture range, will stick together in a ball when squeezed between the hands. Barley that is too dry, will not hold together. Kernels at the correct moisture can be cut with the thumb nail but show no moisture on the cut surface while those too dry cannot be cut.

Swathing is not necessary and can actually reduce yields. Conventional combines, rather than ‘rotary thresh’, are best for harvesting. Combine settings will require adjustments to conventional settings to insure maximum yields with HMB. Producers should check their combine manufacturer’s recommendations for combining HMB to get the correct settings. Field speeds may also need to be reduced.

HMB will not flow as readily as dry grain. The additional water increases the weight that has to be handled during harvest. Handling costs are increased. Therefore, the distance from the field to the storage area is more critical.

Harvesting the crop at a higher moisture level reduces losses of lighter kernels and weed seeds, increasing dry matter yields. Removal of weed seeds, especially wild oats, will reduce the future costs of herbicides.

HMB is harvested before the crop shows a tendency to ‘go down’ or the heads to ‘node over’. This allows the crop to be cut several inches higher than for dry grain. This may be an advantage in areas where additional stubble height may help to control wind erosion, and trap snow for soil moisture conservation. The additional stubble in higher rainfall areas or under irrigation may be more difficult to incorporate into the soil.

Straw from HMB has a better feeding value, since the crop is harvested before leaf losses reduce the feeding value.

Storage

Barley stored at moisture levels above 16% tends to spoil. The risk of spoiling increases with increasing moisture. There are two storage methods used to reduce spoilage in HMB: 1) chemical treatment to control organisms that cause spoilage, and 2) ensiling, where naturally produced chemicals control the organisms that cause spoilage. Most chemical treatments use propionic acid. Several other chemicals such as ammonia, urea and sulfur dioxide have been investigated. None of these have proven satisfactory. Propionic acid is an inconvenient, high cost method of storage usually used only in emergencies.

Ensiling HMB is similar to ensiling other silage crops. The growth of bacteria in the absence of oxygen produces fermentation acids that eventually kill most of the organisms that can cause spoilage. Because low oxygen levels are critical, moisture content and packing are the most important factors affecting the quality of HMB.

Very little work has been done investigating the use of silage additives as aids to fermentation in HMB. Silage additives can contain both the bacteria necessary for fermentation as well as enzymes that breakdown fibre into sugar which serves as a food source for the bacteria. It is likely that naturally occurring bacteria are available in adequate numbers in the barley crop to give good fermentation. Barley contains large amounts of starch that are easily converted to sugar. Silage additives for HMB are not likely cost effective.

Ensiling HMB in oxygen-limiting silos has proven an expensive, inconvenient method of storing the larger quantities of HMB required by feedlots. When utilized both as a storage, and a grain processing system to reconstitute grain year-around, this method of storage has found some use. When large quantities of grain have to be stored economically, a pit silo has proven to be the best system.

While HMB in oxygen limiting silos must be stored whole to facilitate it’s removal from storage, HMB in a pit silo must be processed into the pit to allow sufficient packing to expel trapped oxygen. Processing the barley into storage is a bottleneck in the harvesting operation. A variety of processing methods have been investigated to speed up this process. While barley can be processed only slightly and still be ensiled adequately, it should be processed sufficiently to avoid the cost and inconvenience of having to reprocess it before feeding to insure adequate animal digestion. High capacity roller-mills have proven to be the most satisfactory processing method to meet the requirements of both high capacity and adequate processing. Ensiling requires anaerobic conditions, therefore silos should be as airtight as possible. Covering pits with plastic is essential. Where possible, the plastic covering should extend down the inside surface of the walls of the pit silo. The plastic covering should be held down with old tires placed as close together as possible. Properly stored HMB will have a yellow to light brown colour, a malt odour and a slightly acidic taste.

The exposed face of an open pit of HMB will spoil as a result of exposure to oxygen. Matching the face area to the quantity of HMB needed daily will reduce spoilage. The removal of up to 4 inches of HMB daily will be required during warm weather. Spoilage of HMB in a pit silo is greater than for other silages. Once a silo has been opened it should be used continually.

Feeding

The greatest advantage of HMB is increased crop yield resulting from more light kernels and wild oat seeds being harvested with the grain. As a result HMB and dry barley harvested from the same field are not equal in their nutrient composition. The lighter kernels and wild oat seeds are higher in fibre and lower in starch reducing the energy and increasing protein levels. However, the additional kernel moisture aids in the digestion of the kernel and reduces fines and dust associated with digestive upsets. Animal performance can be expected to be at least equal to dry barley when assessed on a dry matter basis.

Because of the additional weight of water in HMB, cattle must consume more feed to achieve the same level of performance. As a result, shrink of cattle fed HMB is slightly higher. Sale weights have to be calculated with this extra shrink or calculated liveweight yields will be reduced. When liveweight yield is calculated on a fully shrunk basis, then liveweight yield, grade and other carcass characteristics are similar to cattle fed dry barley.

Proper grain processing is critical to animal performance. There has been a tendency to under process HMB to reduce the harvesting bottle neck associated with processing it into the pit. Under-processing has led to the erroneous conclusions that HMB is inferior to dry barley. When properly processed, animal performance is at least equal to dry barley on a dry matter basis.

When formulating rations or purchasing barley for ensiling, it must be remembered that HMB contains more moisture and as a result weights 20 to 25% more than dry barley. Rations have to be balanced on a dry matter basis and purchased HMB corrected for moisture.

Conclusion

There are a number of agronomic advantages of harvesting barley as HMB. The advantages for feeding it are not as numerous. Unless HMB growers are willing to reduce their price, feeders have little incentive to use it. The feeder has to weigh price advantages against the added costs incurred as a result of harvesting, handling, storing, inventory, and storage losses to determine any net advantage. It is likely that HMB production will be limited to areas where wet harvest conditions create sufficient grain price reductions at harvest to justify its use by feeders on a continual basis.

Dwight Karren, MSc., 2000. Alberta Feedlot Management Guide.